A) in this connection must be LPT port set in EPP or ECP mode, but on most motherboards works in SPP mode too.

B) in this connection is for LPT in SPP mode, but on most motherboards works in ECP mode too. Tranzistor NPN is not connected in standard connection as Unipolar tranzistor. But this connection works with bipolar tranzistor well in SPP mode ! ( Try swap E C, but on my 3PC this not works well )